Two-stroke-cycle engine



C. RUDQVIST. TWO-STROKE CYCLE ENGINE.

APPLICATION FILED DEC. 12, 1916.

INVENTOR Car l fiuc iq vist Patented Oct. 4, 1921..

CARI: BUDQVIST, OI MUNICH, GERMANY.

TWO-STROKE-C YCLE ENGINE.

Specification of Letters Patent.

Patented Oct. 4, 1921.

Application filed Ilbeeember 12, 1916. Serial No. 136,582.

To all whom it may concern:

Be it known that I, CARL RUDQVIST, a

of Sweden, and resident of Munich, erman have invented certain new and useful mprovements 1n Two-Stroke-Cycle Engines, whereof the following is a specification.

In certain types of existing two cycle engines the same mixture is used for scavenging and charging purposes, as these two actions are effected simultaneously. T h1s is however, a defect which greatly contributed to this type of engine being superseded by the four cycle engine.

One object of the present invention 18 to improve in two cycle engines the scavenging process in such manner that it occurs n two phases, while the charging operation is entirely separate and distinct from the scavenging process.

To this end ing two parallel c linders, the pistons of which are connecte to a common crank, the crank-shaft being situated in, or approximately in, the middle plane of the two cylinders which have a common combustion chamber and common admission and exhaust ports, controlled by said pistons. On the descent of the piston the air to be used for scavenging is compressed in a known manner in the engine casing and on the up stroke of the piston the air is sucked from the outside through a valve, slide or the like, automatically operated or controlled.

In the scavenging device according to the present invention the scavenging air is first fed into one cylinder through scavenglng ports located in the wall of this cylinder, controlled by the piston, and after the opening of the exhaust port in the other cylinder a portion of the scavenging air flows into such other cylinder through ports in the wall of the same, in such manner that this part of the scavenging air not only drives off the residue of the exhaust gases through the exhaust port in a quicker and more reliable manner, but also owing to the speed at which it rushes through the exhaust port exerts a suction action upon the scavenging air, already admitted nto the first cylinder and which has entered the second cylinder through the common combustion chamber, so that further scavenging of the second cylinder takes place nearly free A from eddy currents.

subject of the Kin I employ an engine comprisp After the closure of the exhaust port at the end of the scavenging operation the admisslon port for the charging mixture is uncovered by the first .c llnder piston and the charge is compresse by aspecial pump, dr1ven from the engine shaft, and fed to the admlssion port under the control of a rotary valve, driven from the engine shaft.

Thls rotary valve, which constitutes a further improvement of the two stroke cycle engine, forms a kind of storage chamher for the charging air or the charging m xture and may communicate, by appropriate ports, with the cylinder and with the charglng pump. Within the casing 'of the rotary valve is a small chamber in the wall of which are suitably positioned ports by means of which such chamber may either be placed in communication with a carbureter or with fresh air or with the charging ump.

By this special construction of the rotary valve, extending across the whole Width of the engine and its arrangement at a right angle to the charging pump the whole structure and operation of the two cycle engine is essentially simplified and improved.

Finally a further improvement of the two cycle engine consists in providing one piston rod with a journal extending over the whole crank pin, while the other piston rod is connected to the first one 'ust above the journal or, if the two are ma e of one piece, is attached to same.

For the purpose of its being journaled on the crank pin it is convenient, the direction of rotation of the crank shaft being that of the hands of a watch, to employ the piston rod of the leading piston and to connect the piston rod of the laggingv piston to the other crank bearing.

By such an arrangement the main pressures, imposing a bending and buckling stress on the crank pin and arising from the leading piston, are on the one hand transmitted directly through its whole length and, on the other hand, a certain elasticity is given the whole gear and thereby, thus even with improper adjustment of the pistons, eccentric grinding of the cylinders is prevented and the action of the inertia forces lessened.

In the drawing a two cycle engine provided with the new improvements is shown in Figures 1 and 2 in two longitudinal sections perpendicular to each other and in' Fig. 3 in a cross section on the line A-B.

Fig. 4 is a section on the line C--D of Fig. 3.

The two cylinders a and b are provided with the pistons c, d, whereof the former leads the latter during the explosion and compression period, and the piston rods e extending over its full ength and the piston rod f is connected at f to the piston rod e.

The engine casing it serves as a scavenging air chamber and. is automatically or in a controlled manner supplied, through a valve or slide, with the outer air. v

- The admission port for the mixture of fuel and air, common to the two cylinders a, b is denoted by i, the common combustion chamber by is and the common exhaust port by Z.

The scavenging air leaves, on the one hand, the crank casing h by the ports 97?, located in the wall of the cylinder 1) under control by the piston (Z, and enters, on the other hand, by the openings m provided in the wall of the cylinder at behind the partition wall it of the casing h. Consequently the cylinder b is first of all scavenged by the air issuing through the ports m, which air drives the exhaust, gases through the ports n into the conduit Z. The exhaust of the remainin portion of the burnt gases and the comp etion of the process of scavengingthe cylinder (11 is effected by the scavenging air streaming out of the ports m which produces a sucking action on the contents of the cylinder 12, thereby completely cleaning the same from the burnt gases.

After the completion of the scavenging and the exhaust process'the charge is admitted which is produced by the charging pump 0, the piston p of which is driven by the eccentric 1', directly mounted on the engine shaft at the end opposite to the flywheel'q, and the piston rod 8.

The charging pump 0 communicates by a pipe t with the charging valve u, 41, extending across the whole width of the engine, in the casin w and driven from the flywheel-side o the engine by a chain-gearing a: or the like.

The chamber u of the valve serves as a collector for the mixture and communicates, by the port u, with the admission-opening i, and a second port u cooperates with the piping t.

The chamber it has formed therein, opposite to the connecting end of the piping t and the port u respectively, the chamber o, provided with a port '0 arranged at its outer periphery and diametrically opposite to the port u with regard to the axis of to secure by Letters feed in due time into the cylinders an easily controllable quantity of mixture, thereby greatly increasing the useful work of the engine, this being also due to the nature of the admission.

What I claim as m invention and desire atent is 1. In a two cycle internal combustion engine, the combination with a casing having a compressed air chamber therein, of a air of cylinders within said casing the wal of each cylinder having openings through which compressed air from said. chamber may flow, a combustion chamber common to both cylinders at one end thereof, a fuel admission passage communicating with one of said cylinders, an exhaust passage communieating with the other of said cylinders, a

the compressed air chamber to scavenge such chamber and thereafter the second piston is moved to uncover thevope-nings therein and the exhaust passage whereby compressed air will flow through said last named openings to cause a suction action in both cylinders and complete the scavenging 0 eration.

2. n a two cycle internal combustion engine, the combination with a casing having a compressed air chamber therein, of a pair of cylinders within said casing the wallof each cylinder having openings through which compressed air from said chamber may flow, a combustion chamber common to both cylinders at one end thereof, a fuel admission passage communicating with one of said cylinders, an exhaust passage com- 1 municating with the other of said cylinders, a piston operable in each cylinder, certain of the openings in the cylinder adjacent the exhaust passage being adapted to communicate with the latter, and means for operating said pistons to first uncover the openings in the cylinder adjacent the fuel admission passage and thereafter uncover the. openlngs in the cylinder adjacent the exhaust passage whereby a suction effect is produced in said air leading from-the other cylinder, said cylinder adjacent the fuel passage having openings communicating with the compressed air chamber, and said cylinder adjacent the exhaust passage having openings certain of which communicate with said compressed air chamber and others of which communicate with said exhaust passage, a piston movable in each cylinder, and means for operating said pistons whereby the openings in the cylinder adjacent the admission passage are first uncovered to admit a charge of scavenging air to said cylinders and thereafter the openings in the other cylinder are uncovered to ermit the passa e of compressed air theret rough to the ex aust passage and the creation of a suction action in said cylinders.

41. In a two cycle internal combustion englue, the combination with a casing having a compressed air chamber therein, of a pair of cylinders within said casing, a combustron chamiber common to both cylinders, a fuel admission passage leading to one of said cylinders and an exhaust passage leading from the other cylinder, said first named cylinder having openings communicating with the compressed air chamber and said second named cylinder having openings certam of which communicate with the air chamber and others of which communicate with the exhaust passage, a partition adjacent the second named cylinder for separatmg the openings therein which communicate with the compressed air chamber from those which communicate with the exhaust passage, a piston movable in each cylinder, and means for operating said pistons whereby the openings in the first named cylinder are uncovered before those in the second named cylinder.

5. In a two cycle internal combustion engme, the combination with a casing having a compressed air chamber therein, of a pair of cylinders within said casing the wall of each cylinder having openings through which compressed air from said chamber may flow, a combustion chamber common to both cylinders at one end thereof, a fuel admission passage communicating with one of said cylmders, an exhaust passage communicating with the other of said cylinders, a piston operable in each cylinder, means for operating said pistons whereby the openings in the cylinder communicating with the admission passage are first uncovered to the flow of compressed air from the compressed air chamber to scavenge such chamber and thereafter the second piston is moved to uncover the openings therein and the exhaust passage whereby compressed air will flow through said last named openings to cause a suction action in both cylinders and complete the scavenging operation, and a valve for controlling the admission of fuel to said engine, said valve comprising a chamber adapted to receive fuel and supply the same to the fuel admission passage and an additional chamber within the first named valve chamber and adapted to communicate with a. carbureter.

6. In a two cycle internal combustion engine, the combination with a casing having a compressed air chamber therein, of a pair of cylinders within said casing the wall of each cylinder having openings through which compressed air from said chamber may flow, a combustion chamber common to both cylinders at one end thereof, a fuel admission passage communicating with one of said cylinders, an exhaust passage communicating with the other of said cylinders, a piston operable in each cylinder, means for operating said pistons whereby the openings in the cylinder communicating with the admission passage are first uncovered to the flow of compressed air from the compressed air chamber to scavenge such chamber and thereafter the second piston is moved to uncover the openings therein and the exhaust passage whereby compressed air will flow through said last named openings to cause a suction action in both cylinders and complete the scavenging operation, and a valve for controlling the admission of fuel to said engine, said valve comprising a fuel chamber having a fuel admission port adjacent one of its ends, said fuel chamber adapted to receive fuel and supply the same to the fuel admission passage, and an additional chamber within the fuel chamber and adapted to communicate with a carbureter.

In testimony whereof I have signed this specification in presence of two subscribing witnesses.

CARL RUDQVIST.

Witnesses WV. S. SPIEGELBERG, A. DIEHL. 

